Sure, here's an example of how you can implement a simple Atari Pong game using JavaScript in a single HTML file. Please note that this is just a basic implementation and can be expanded upon to add more features and complexity as desired.
This implementation sets up a canvas element where the game is displayed. The player controls one paddle on the left side of the screen, and the computer controls the other paddle on the right side. The goal is to bounce the ball off the paddles and prevent it from going past your own paddle.
You can control the player paddle on a smartphone by sliding your finger up and down the screen. The computer-controlled paddle moves automatically to track the ball's movement. The game loop continuously updates the game state and redraws the elements on the canvas.
Note that this is a simplified version of Pong and does not include features such as scorekeeping or win conditions. You can further enhance the game by adding these features and improving the gameplay mechanics.